Lecture 4: Development of T and B cells in primary lymphoid tissues and T-cell mediated immunity. Flashcards
What is the term tolerance in immunology?
How effector B and T cells must have a potential to recognize and respond against foreign or dangerous antigens but ignore normal or self antigens.
Where is tolerance established?
Created during T and B cells development in their primary lymphoid tissues, must be successfully completed before naive lymphocytes can enter the periphery.
For T cells, the TCR receptor transduction pathways.
For B cells, the BCR receptor transduction pathways.
What terms describe lymphocyte development in primary lymphoid tissues?
Positive selection
Negative selection
What is positive selection?
What is negative selection?
What are naive lymphocytes?
Lymphocytes that have passed the tolerance tests in primary lymphoid tissues but not yet activated by encountering target antigen.
What is the thymus?
A small gland in the lymphatic system, it makes and ‘trains’ T cells.
Thymus is fully developed at birth.
Most active before puberty, after this it begins to shrink and education of ‘new’ T cells decreases.
What characteristics do T cells have when they enter the thymus?
They lack most surface molecules that mature naive T cells have, TCR genes are not rearrange yet.
What key phrases are there when differentiating T cell types in their development in the thymus?
DN: Double negative
DP: Double positive
SP: Single positive
What are thymic cortical T-cell nurseries?
Which T cells detect MHC I and MHC II?
CD4+ (helper) detect MHC type II
CD8+ (cytotoxic) detect MHC type I
What is the autoimmune regulator? (AIRE)
AIRE is a protein that controls gene expression in thymic medulla epithelial cells (mTEC).
What are Treg cells?
Regulatory T cells that function to suppress immune response, maintaining homeostasis and self-tolerance. Can inhibit T-cell proliferation and cytokine production.
Where do B cells develop?
In the bone marrow.
